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The memory of the accreting plate boundary and the continuity of fracture zones

Earth and Planetary Science Letters

By:
and
DOI: 10.1016/0012-821X(82)90130-3

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Abstract

A detailed aeromagnetic anomaly map of the Mesozoic seafloor-spreading lineations southwest of Bermuda reveals the dominant magnetic grain of the oceanic crust and the character of the accreting boundary at the time of crustal formation. The magnetic anomaly pattern is that of a series of elongate lobes perpendicular to the fracture zone (flowline) trends. The linear sets of magnetic anomaly peaks and troughs have narrow regions of reduced amplitude anomalies associated with the fracture zones. During the period of Mesozoic geomagnetic polarity reversals (when 1200 km of central North Atlantic seafloor formed), the Atlantic accreting boundary consisted of stationary, elongate, spreading center cells that maintained their independence even though sometimes only minor spatial offsets existed between cells. Normal oceanic crustal structure was formed in the spreading center cells, but structural anomalies and discontinuities characteristic of fracture zones were formed at their boundaries, which parallel flowlines of Mesozoic relative plate motion in the central North Atlantic. We suggest that the memory for a stationary pattern of independent spreading center cells resides in the young brittle lithosphere at the accreting boundary where the lithosphere is weakest; here, each spreading center cell independently goes through its cylce of stress buildup, stress release, and crustal accretion, after which its memory is refreshed. The temporal offset between the peaks of the accretionary activity that takes place within each cell may provide the mechanism for maintaining the independence of adjacent spreading center cells through times when no spatial offset between the cells exists.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The memory of the accreting plate boundary and the continuity of fracture zones
Series title:
Earth and Planetary Science Letters
DOI:
10.1016/0012-821X(82)90130-3
Volume
59
Issue:
2
Year Published:
1982
Language:
English
Publisher:
Elsevier
Contributing office(s):
Coastal and Marine Geology Program
Description:
12 p.
First page:
255
Last page:
266
Other Geospatial:
North Atlantic
Online Only (Y/N):
N
Additional Online Files(Y/N):
N